use DBI;
$dbh = DBI->connect("DBI:CSV:f_dir=./");
$query = "select id, fname, lname";
$sth->prepare($query);
$sth->execute();
while ($rowdata = $sth->fetchrow_hashref) {
    $hash{$rowdata->{'id'}} = $rowdata{'id'};
    if ($rowdata->{'fname'}) { $hash{$rowdata->{'id'}}{'fname'} = 1; }
    if ($rowdata->{'lname'}) { $hash{$rowdata->{'id'}}{'lname'} = 1; }
}

print Dumper(\%hash);